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Biomedical subjects

C M Greven

Publications and source records attributed to C M Greven.

35 records · Page 2Linked to original sources
PubMed1994

Intraocular silicone oil: in vitro and in vivo MR and CT characteristics.

PURPOSE: To describe the CT and MR characteristics of intraocular silicone oil (polydimethylsiloxane), which is used with increasing frequency to treat complicated retinal detachments. METHODS: CT was performed on a silicone oil/water phantom and on a patient with retinal detachments secondary to cytomegalovirus retinitis, treated by bilateral intraocular injections of silicone oil. CT appearance and CT number of silicone oil were evaluated. Proton MR spectroscopy was performed with a 200-MHz spectrometer on a sample of polydimethylsiloxane within a tube of deuterated water. MR imaging was performed on a silicone oil/water phantom and on two patients with retinal detachments treated with silicone oil injection. RESULTS: Silicone oil is relatively radiodense; its CT attenuation is approximately 130 HU. On spectroscopy, silicone oil gave a single peak at 0.33 ppm. Relative to water silicone oil was hyperintense on T1-weighted images and hypointense on spin-density and T2-weighted images. Estimated T1 and T2 were 716 msec and 68 msec, respectively. Chemical shift artifacts were seen on MR images and were exaggerated when a narrow sampling bandwidth was used. In clinical cases spectral saturation pulses normally used for lipid suppression could be adjusted to saturate only the silicone resonance; in this way, the chemical shift artifact was eliminated. CONCLUSION: Intraocular silicone oil has unique imaging characteristics with which radiologists must become familiar. These characteristics include high attenuation on CT and hyperintensity on T1-weighted MR, both of which may mimic hemorrhage. Elimination of the prominent chemical shift artifact on MR with selective saturation of the silicone resonance improves evaluation of the globe.

AIDS-Related Opportunistic Infections↗
PubMed1992

Posterior chamber intraocular lens implantation combined with lensectomy-vitrectomy and intraretinal foreign-body removal.

Two patients with intraretinal foreign bodies and traumatic cataracts were treated with pars plana lensectomy, vitrectomy, and removal of the foreign body. In each case, it was technically possible to preserve the anterior capsule despite small but obvious rents caused by the foreign body. This allowed support for the placement of a posterior chamber intraocular lens at the time of the initial repair. Posterior chamber intraocular lens implantation may be a useful adjunctive step in the treatment of selected patients with intraocular foreign bodies.

Adult↗
PubMed1992

Acquired immunodeficiency syndrome-related primary intraocular lymphoma.

A 37-year-old man with acquired immunodeficiency syndrome and cytomegalovirus retinitis developed primary intraocular and central nervous system lymphoma. Intraocular involvement was documented before death with vitrectomy. Autopsy demonstrated the presence of cytomegalovirus retinitis in the right eye and lymphoma in both eyes and the brain. We believe this is the first report of autopsy-confirmed primary intraocular lymphoma in a patient with the acquired immunodeficiency syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Pseudophakic retinal detachments. Anatomic and visual results.

Retinal reattachment rates and visual results were analyzed in 227 consecutive primary pseudophakic rhegmatogenous retinal detachments. The overall anatomic reattachment rate was 90%, with no significant difference between the anterior chamber (AC) and posterior chamber intraocular lens groups. Visual results were significantly worse in the AC lens group (P less than 0.05). Negative prognostic indicators for reattachment included age greater than 65 years, poorer preoperative vision, larger extent of the retinal detachment, inability to identify a retinal break, longer duration of symptoms before presentation, and grades C or D proliferative vitreoretinopathy (P less than 0.05). In addition to the above factors, eyes with AC reaction, AC lenses, and macular detachment had a poorer visual prognosis.

Adult↗
PubMed1992

Vitreoretinal surgical technique for transplanting retinal pigment epithelium in rabbit retina.

Transplantation of retinal pigment epithelial (RPE) cells has been proposed as a potential remedial procedure for previously untreatable retinal diseases. In this study, a vitreoretinal surgical technique was used to transplant pigmented RPE cells obtained from pigmented rabbits into the subretinal space of New Zealand White rabbits. At the time the animals were sacrificed, the retina was re-attached in all but 4 of the 24 experimental eyes. Histologically, by one week the transplanted RPE cells had formed a monolayer in patchy areas beneath the attached retina. By electron microscopy, RPE cells with prominent melanin granules were found attached to Bruch's membrane. Three weeks after transplantation, grafted RPE cells had formed apical microvilli and tight junctions with adjacent cells. The nucleus of the cells containing pigment had become oval, and their contact with Bruch's membrane appeared to be composed of bsal infoldings that were well formed. Our findings demonstrated the functional appearance of the transplanted RPE cells.

Animals↗
PubMed1991

Cutaneous malignant melanoma metastatic to the choroid.

Cutaneous malignant melanoma metastatic to the eye is a well-documented occurrence in the ophthalmic literature. Typically, ocular metastatic disease occurs concomitantly with or following the documentation of disseminated metastases. We present the clinical and histopathologic findings in a 62-year-old man whose first manifestation of metastatic cutaneous melanoma was his choroidal lesion.

Choroid Neoplasms↗
PubMed1991

Protein S deficiency and bilateral branch retinal artery occlusion.

A macular branch retinal artery occlusion developed in the right eye of a 25-year-old woman when she was 38 weeks pregnant. She subsequently presented 5 days postpartum with a branch retinal artery occlusion in her left eye. Although her initial work-up did not reveal a source for her occlusions, subsequent studies have documented a deficiency of protein S.

Adult↗
PubMed1990

The use of intravitreal air in selected retinal detachments.

Statistically controlled studies substantiating the current widespread acceptance of intravitreal air injection as an adjunct to traditional or standard scleral buckling techniques in the repair of rhegmatogenous retinal detachment are unavailable. The surgical success rate of a prospectively chosen group of patients who received intravitreal air was compared with that of a retrospectively chosen but comparable group of patients who did not receive air injection in their detachment repair. The 100% retinal reattachment rate in the air group at six weeks was found to be statistically significant for comparable configurations of retinal detachment and superiorly located breaks in patients without significant proliferative vitreoretinopathy.

Aged↗
PubMed1989

Flurbiprofen sodium to prevent intraoperative miosis during vitreoretinal surgery.

To assess the efficacy of flurbiprofen sodium 0.03% at maintaining pupillary dilation during vitreoretinal surgery, we performed a randomized, double-masked, controlled trial of 139 consecutive patients. The mean decrease in pupil size during surgery in patients who received flurbiprofen was 0.9 mm; for patients who did not receive the drug it was 0.8 mm. The type of surgery performed (vitrectomy or scleral buckle), gender, age, lens status, and a history of diabetes or previous intraocular surgery were assessed and the addition of flurbiprofen to routine preoperative dilation did not significantly affect the mean change in pupil size for any of these subgroups. Of the nine patients who developed at least 3 mm of miosis, five received flurbiprofen and four did not. Use of flurbiprofen did not appear to reduce intraoperative miosis during vitreoretinal surgery in a clinically meaningful manner.

Adolescent↗
PubMed1989

Rhegmatogenous retinal detachment following cryotherapy in retinopathy of prematurity.

Three patients who had been treated with transscleral cryotherapy to the avascular retina for stage 3+ retinopathy of prematurity with threshold disease had total rhegmatogenous retinal detachments develop. In each case, the retinal detachment developed more than 1 year after treatment and resulted from a tear at the junction of the treated and untreated retina. Rhegmatogenous retinal detachment is a late complication of transscleral cryotherapy that to our knowledge has not previously been documented.

Child, Preschool↗
PubMed1989

The spectrum of cavitary optic disc anomalies in a family.

The current classification of cavitary optic disc anomalies including the morphologically related entities--optic nerve pit, morning glory disc anomaly, coloboma of the optic nerve, and retinochoroidal coloboma involving the optic nerve--is inexact and confusing. Traditionally, these disc abnormalities have been regarded as distinct morphologic anomalies. Thirty-five members of a five-generation kindred with autosomal dominantly inherited optic disc anomalies were examined. Observed abnormalities in this pedigree comprised a spectrum of morphologic variants ranging from large anomalous discs to typical pits and colobomas. The findings in this family suggest a variable expression of a single autosomal dominant defect rather than the chance occurrence of three separate, distinct, but morphologically similar entities occurring in a single pedigree.

Chromosome Aberrations↗
PubMed1988

Epiretinal membrane release and posterior vitreous detachment.

The spontaneous release of epiretinal membranes is a rare clinical phenomenon, the mechanism of which is poorly understood. The authors present three patients with epiretinal macular membranes associated with peripheral retinal lesions, in whom spontaneous release of the membrane occurred in conjunction with detachment of the posterior vitreous. In each patient, the membrane remained attached to the posterior vitreous face, and in each eye there was a decrease in retinal striae and an improvement in vision. The authors postulate that posterior vitreous separation was the mechanism by which these membranes detached from the macula.

Adult↗